In a mobile communication, a plurality of states are defined based on traffic amounts to be transmitted for the purpose of saving battery of a mobile station and improving radio resource use efficiency of a radio access network.
More particularly, defined states are a dedicated channel state (CELL_DCH) in which communication is performed using a dedicated channel when a traffic amount to be transmitted is large, a common channel state (CELL_FACH) in which communication is performed using a common channel when the traffic amount to be transmitted is small, and discontinuous reception state (CELL_PCH or URA_PCH) in which paging indicator is discontinuously received when there is no traffic to be transmitted, and transition among the states takes place according to the traffic amounts to be transmitted as shown in FIG. 1.
For performing the state transition according to the traffic amount to be transmitted, it is necessary to switch between communication channels. In this case, for example, as shown in FIG. 2, in a radio access network including a mobile station 1 and a radio access network apparatus 2, a channel setup request signal and a channel setup response signal are necessary between the mobile station 1 and the radio access network apparatus 2.
For example, an example of the channel setup request signal is described with reference to FIG. 3. In this example, in a case in which a mobile station in the CELL_PCH state changes the state to the CELL_DCH state, channel setup between the mobile station 1 and the radio access network apparatus 2 is described.
The radio access network apparatus 2 sends paging information to the mobile station 1. The mobile station 1 reports a current cell (CELL UPDATE).
Next, the radio access network apparatus 2 confirms that a cell is reselected and sends a signal specifying a physical channel to be used for communication (CELL UPDATE CONFIRM).
Next, the mobile station 1 reports that reconfiguration of the physical channel is completed.